Active-Passive Photonic Integrated Circuit with Intermediate Waveguide Coupling

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Solution Overview

Problem

Current photonic integrated circuits (PICs) face challenges in efficient optical coupling between dissimilar materials with different refractive indices, leading to scaling limitations and high packaging costs due to the need for precise alignment, and are limited by material absorption and maximum optical intensity, especially when using silicon or indium phosphide.

Innovation Solution

The method involves wafer bonding and deposition of dissimilar materials using a butt-coupling scheme with an intermediate layer for mode conversion, allowing efficient optical coupling between high-refractive index active layers and low-refractive index passive waveguides without the need for prohibitively narrow taper tips, enabling scalable integration of high-performance amplitude and phase modulators with active gain media.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If taper structures are used to transfer optical modes between materials with dissimilar refractive indices, then optical coupling efficiency is improved, but the requirements on taper tip dimensions become prohibitively narrow (nanometer scale) which increases manufacturing complexity and cost

Engineering Contradiction:

Improveoptical coupling efficiencyVSAvoidtaper tip dimension requirements

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces an intermediate waveguide layer with refractive index between the high-index active material and low-index passive waveguide. This intermediate layer acts as a mediator that gradually transitions the optical mode from the high-index to low-index material, eliminating the need for extremely narrow taper tips while maintaining efficient optical coupling.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If hybrid approach with separately processed chips is used, then material selection flexibility is improved, but precise alignment is required which increases packaging costs and introduces scaling limitations

Engineering Contradiction:

Improvematerial selection flexibilityVSAvoidpackaging complexity and scaling

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent merges the active and passive waveguide structures into a single integrated platform where the intermediate waveguide layer is formed as part of the same fabrication process. This combining eliminates the need for separate chip processing and precise alignment, enabling scalable manufacturing while maintaining material selection flexibility.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The intermediate waveguide layer is formed preliminarily during the fabrication process before final device assembly. This preliminary formation of the coupling layer ensures proper refractive index matching is established in advance, eliminating the need for post-fabrication alignment adjustments.

Inventive Principle:

Principle #10Preliminary action

3Power

If conventional waveguide materials like SiN, TiO2, Ta2O5, AlN are used, then high-power handling and transparency at shorter wavelength are improved, but refractive indices are lower which requires even narrower taper tips for efficient coupling

Engineering Contradiction:

Improveoptical power handling capabilityVSAvoidtaper tip width requirements

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables efficient optical coupling, scalable manufacturing, and operation over a wide wavelength range, handling high optical power with reduced optical losses and relaxed requirements on taper tip dimensions, facilitating the integration of high-performance modulators and detectors.

Implementation Method 1

transfer the optical mode efficiently from the active waveguide to the passive waveguide

Methodology Applied

Scientific EffectMode conversion: Waveguide (optics)

Implementation Method 2

transfer the optical mode efficiently from the active waveguide to the passive waveguide

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentUS12092871B2Active-passive photonic integrated circuit platform

Publication Date: 2024.09.17 NEXUS PHOTONICS INC

AI summary

A device has a plurality of waveguide structures including two active (one of which comprises two sub-layers), two passive, and three intermediate waveguide structures on a common substrate. At least partial butt coupling between active and intermediate waveguide structures, and tapering in the intermediate and/or passive waveguide structures at each junction therebetween facilitates efficient optical mode transformations as optical signals travel through the device, either from a first sub-layer of the first active waveguide structure through the other sub-layer, then sequentially though a first intermediate waveguide structure, a passive waveguide structure, a second intermediate waveguide structure, a second active waveguide structure, a third intermediate structure, and a second passive waveguide structure; or in reverse from the second passive waveguide structure back through to the first sub-layer of the first active waveguide structure. Lithographic alignment marks facilitate precise mutual alignments between layers defining each of the waveguide structures.